Devices for example for continuous strip casting or conventional facilities for rolling strip material are normally driven by a single motor drive. The synchronization of the pair of rolls is usually performed by a grooved roller gear between the drive and the casting or rolling device. Step-down gears accommodating the ratio of turning speeds of the drive and the individual rolls are then required.
This combined step-down grooved roller gearing or, if no speed reduction is necessary, the appropriate grooved roller gearing is always a special construction, which is expensive to purchase and very problematic to maitain. The break-down of grooved roller gearing usually results in a long period of down time in production.
Furthermore, the diameters of the rolls which should run in synchrony have to be matched within relatively close tolerance limits. However, with known devices for rolling and in particular with roll-type strip casters the wear on the rolls is very heavy. After a certain time therefore these rolls have to be removed and reground. As the wear on the rolls is usually non-uniform, the diameter of the rolls has to be reduced by a greater amount than would in fact be necessary. As a rule the cost of purchasing new rolls represents a significant factor in the running costs.